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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Metodologia para avaliação da capabilidade de controle de superfícies técnicas usinadas em torno de ultraprecisão / Methodology to assess the capability of the control technical surfaces in ultraprecision turning manufacturing

Camargo, Rosana 21 November 2005 (has links)
A nanotecnologia não é mais um sonho, já faz parte da nossa realidade, do nosso dia a dia. É considerada, por muitos, a quinta Revolução Industrial, uma revolução tecnológica de grande abrangência, que poderá causar impactos talvez sem precedentes na história. A soma anual dos investimentos nesta nova tecnologia é de bilhões de dólares. Devido às inovações oriundas da nanotecnologia, os processos da manufatura e a medição de ultra-precisão vêm se desenvolvendo a cada dia. A nanotecnologia fez da usinagem de ultraprecisão com ferramenta de diamante uma grande aplicação na produção de itens de alto volume, tais como: disco de memória de computadores, lentes de contato, moldes de dentes, cilindros para impressão, espelhos metálicos. A alta integridade da superfície é requerida em todos os itens obtidos por este processo. Em conseqüência, é necessário um método de medição que seja o mais exato possível, isto é, que chegue a resultados o mais próximo possível do valor verdadeiro. Mas o que significa exatidão para uma análise ideal da superfície, uma vez que não existe referência para isso? Superfícies têm sido avaliadas por meio da medição da rugosidade, a qual consiste na determinação de um valor médio, de vários setores, dentro de valores limites preestabelecidos. A metrologia, através de seus métodos e princípios, é um importante instrumento para validar modelos e teorias. O conceito que \"uma vez testado, passa a ser aceito em qualquer lugar\". Daí a crescente necessidade de resultados de medições confiáveis que possam ser validados em qualquer lugar e a qualquer tempo. Assim, um caminho a ser seguido é o de se entenderem profundamente todos os métodos e princípios envolvidos nas operações de medição de rugosidade. E para que um método seja metrologicamente válido (ou aceitável), faz-se necessário realizarem-se comparações de diversas medições, de um mesmo mensurando, utilizando métodos diversos. Havendo discrepância nos resultados, é uma evidência de que as premissas e hipóteses levaram a acreditar que a teoria ou modelo adotado deve ser reavaliado. Este trabalho selecionou os três métodos mais utilizados na caracterização da integridade de superfícies técnicas obtida em torneamento de ultraprecisão com diamante, e descreveu uma metodologia para a avaliação da capabilidade do processo de controle de superfícies técnicas usinadas em torno de ultraprecisão. / Nanotechnology is no longer a dream. It is part of the real world. It is considered by many people as the fifth Industrial Revolution, a technological revolution of great impact in history. The world annual investment in this technology reaches billions of dollars. Due to innovations related to nanotechnology, ultraprecision manufacturing processes and metrology is developing steeply. Nanotechnology made single point diamond turning an important mass production process of, for instance, computer hard discs, contact lenses, moulds, printer cylinders, metallic mirrors, etc. High grade surface integrity is required of items produced by this process. As a consequence, it is necessary to use a measurement method which is most accurate as possible, i.e., resulting in a value as close as possible to the true. But what does true mean if there is no reference for that? Surfaces have been assessed by roughness measurements which determines a mean value of several sectors within pre-determined limits. Metrology, with its methods and principles, is an important instrument to validate models and theories. The concept, once tested, becomes accepted everywhere. Therefore the increasing necessity of reliable measurement results which may be validated anywhere and any time. Thus, it is essential a deep understanding of all methods and principles involved in roughness metrology operations. For a method to be metrologically accepted, it is necessary that it is compared with different methods. In the event of existing discrepancies, the premisses and hypotheses which fundamented the theory or model should be reassessed. Three of the most used methods have been selected to characterize the surface integrity of technical surfaces generated by diamond turning. A methodology to assess the capability of the process of control of those surfaces is proposed.
12

Análise de precisão dos posicionamentos relativo e por ponto simples para bases curtas, com o sistema NAVSTAR/GPS: estudo de caso em Belém-PA / Analysis of precision of the relative positionings and for single point for short bases, with the system NAVSTAR/GPS: study of case in Belém-PA

Silva, Carlos Augusto Uchôa da 28 April 2000 (has links)
Este trabalho constitui-se num método para estudo, implantação e análise de precisão dos posicionamentos relativo e por ponto simples para vetores de linhas bases curtas com o GPS. Para isso, o autor elegeu, nomeou e observou com receptores GPS 21 pontos geodésicos na região metropolitana de Belém-PA, denominada de malha GPS99. Simultaneamente mediu dados meteorológicos \"in loco\" através de medições psicrométricas. As condutas organizadas para processamento dos dados diferem entre si em: tipos de correções inseridas e resultados analisados. Estes resultados são comparados entre si para a apresentação de análises, conclusões e recomendações acerca de diferentes fatores: PPP, L1 versus L3, Resolver ou fixar ambiguidade, inserir ou não variáveis meteorológicas reais para bases curtas, posicionamento relativo versus ponto simples, variação do ponto simples e influência da pressão atmosférica na precisão final de uma observação GPS. Adicionalmente é apresentada e discutida a metodologia PPP, desenvolvida pelo JPL. / The constitution of this work is a method for the study, introduction and analysis of precision of the relative positionings and for simple point to vectors of short base with the GPS. For this, the author elected, designated and observed with GPS receivers 21 geodesic points in the metropolitan region of Belém-PA, denominated of GPS99 net. Simultaneously methereological data were measured \"in loco\" through the psychometric measurements. The procedures to the data processing are different among them: types of inserted correction and analysed results. These results are compared among them to the presentation of analyse, conclusions and recommendations considering different factors: PPP L1 versus L3; solve of fix ambiguity insert or no real methereological variables to short base, relative positioning versus simple point, variation of the simple point and influence of atmospheric pressure into the final pressure of one GPS observation. Additionally the PPP methodology developed by JPL.
13

Avaliação da integridade superficial do polimetilmetacrilato (PMMA) no torneamento com ferramenta de diamante / Evaluation of the surface integrity of polymethymethacrylate (PMMA) in diamond turning tool

Renê Mendes Granado 10 August 2006 (has links)
O torneamento com ferramenta de diamante é um processo de fabricação usado para a produção de componentes ópticos com alta precisão de forma e qualidade óptica final. O crescente uso de materiais poliméricos na industria, particularmente em equipamentos de precisão eletrônica e óptica tem exigido o estudo e entendimento de suas características e propriedades específicas. Esse trabalho avalia a integridade superficial do polimetilmetacrilato torneado com ferramenta de diamante, com relação à transmitância. Os parâmetros de usinagem objetivaram a obtenção de superfície gerada no modo dúctil. As rotações usadas foram 550 e 1000 rpm, a faixa do avanço variou de 5 a 20 µm/rev e a profundidade de usinagem de 4 e 10 µm. Duas ferramentas com geometrias diferentes foram usadas nos testes, com ângulos de saída de -5° e +5°, com raios de ponta de 1,143mm e 1,524 mm. A superfície final e morfologia dos cavacos foram avaliadas por microscopia eletrônica de varredura e a transmitância medida por espectofotometria. A integridade superficial foi claramente influenciada pelo ângulo de saída da ferramenta como observado na literatura. Devido a formação de cavacos no regime dúctil, a superfície final apresentou microtrincas em função do fluxo viscoelástico. A menor rugosidade obtida foi de 33,2 nm para a condição de corte de 10 µm/rev e 10 µm de profundidade de usinagem. Quando os resultados foram comparados as lentes injetadas, observou-se que o valor da transmitância são muito similares. / Single point diamond turning is a manufacturing process used to fabricate optical and precision components with high form accuracy and optical quality surface finish. The increase in the use of polymer materials in industry, particularly in electronic and optic precision devices, has demanded the study and understanding of its specific characteristics and properties. This work is addressed to the evaluation of the surface integrity of diamond turned polymethylmethacrilate regarding the trade off surface integrity versus transmitance. The cutting conditions were selected in order to work within the ductile mode material removal range. The spindle speed were 550 and 1000 rpm, feed rate ranging from 5 up to 20 micrometer/rev and the depth of cut ranging from 4 up to 10 micrometer. Two different tool geometries were used in the tests, a -5 \'DEGREES\' and +5 \'DEGREES\' rake angles with round nose radius tools of 1,143 mm and 1,524 mm. Surface finish and morphology of the chips was evaluated by scanning electron microscopy and transmitance measured by spectophometry technique. The surface integrity was clearly influenced by the cutting tool rake angle as observed in literature. Despite the formation of ductile chips the surface finished presented microcracks likely due the instability of the viscoelastic flow. The lower surface roughness obtained was 33,2 nm Ra for the cutting condition of 10 micrometer/rev and 10 micrometer depth of cut. When the results were compared with injected lenses, it was observed that the value of transmittance was very similar.
14

Análise de precisão dos posicionamentos relativo e por ponto simples para bases curtas, com o sistema NAVSTAR/GPS: estudo de caso em Belém-PA / Analysis of precision of the relative positionings and for single point for short bases, with the system NAVSTAR/GPS: study of case in Belém-PA

Carlos Augusto Uchôa da Silva 28 April 2000 (has links)
Este trabalho constitui-se num método para estudo, implantação e análise de precisão dos posicionamentos relativo e por ponto simples para vetores de linhas bases curtas com o GPS. Para isso, o autor elegeu, nomeou e observou com receptores GPS 21 pontos geodésicos na região metropolitana de Belém-PA, denominada de malha GPS99. Simultaneamente mediu dados meteorológicos \"in loco\" através de medições psicrométricas. As condutas organizadas para processamento dos dados diferem entre si em: tipos de correções inseridas e resultados analisados. Estes resultados são comparados entre si para a apresentação de análises, conclusões e recomendações acerca de diferentes fatores: PPP, L1 versus L3, Resolver ou fixar ambiguidade, inserir ou não variáveis meteorológicas reais para bases curtas, posicionamento relativo versus ponto simples, variação do ponto simples e influência da pressão atmosférica na precisão final de uma observação GPS. Adicionalmente é apresentada e discutida a metodologia PPP, desenvolvida pelo JPL. / The constitution of this work is a method for the study, introduction and analysis of precision of the relative positionings and for simple point to vectors of short base with the GPS. For this, the author elected, designated and observed with GPS receivers 21 geodesic points in the metropolitan region of Belém-PA, denominated of GPS99 net. Simultaneously methereological data were measured \"in loco\" through the psychometric measurements. The procedures to the data processing are different among them: types of inserted correction and analysed results. These results are compared among them to the presentation of analyse, conclusions and recommendations considering different factors: PPP L1 versus L3; solve of fix ambiguity insert or no real methereological variables to short base, relative positioning versus simple point, variation of the simple point and influence of atmospheric pressure into the final pressure of one GPS observation. Additionally the PPP methodology developed by JPL.
15

Study on structural improvement and mooring line fatigue risk analysis for a single point mooring system

Pan, Jen-Ya 14 August 2007 (has links)
The purpose of this report is not only to improve the cage volume deformation problem during typhoon attack but also to perform the risk analysis for a single-point-mooring (SPM) net cage system when employed in the open sea. This SPM cage system has advantages over the traditional multi-mooring lines cage system, especially when the water depth is deeper than 50m, which may prohibit divers from checking the security of anchors as well as installing the mooring system at a precise position due to the difficulty in deploying anchors in the deep and restless ocean. But the SPM cage system has no such deploying problems, and yet offers some benefits such as: (1) having environmental eco-friendly feature, the uneaten feeds could spread in a vast area and thus reduce the intensity of pollution, (2) employing only one mooring line means saving a lot of construction cost, (3) a precise location is not required and thus relatively easier to be installed at any sites, and (4) easier to connect or remove cages from the mooring system. So far the SPM cage systems have become one of the most potential cage systems in the world. For example, Israel and Canada have individually developed their own SPM cage systems. This study also follows this trend and focuses on developing a new system which is suitable to Taiwan marine environment. The numerical model for cage motion equations are solved based on the lumped mass method which produces the maximum mooring line strength and the minimum of the volume deformation. As for the risk analysis for mooring line consists of two procedures: at first to form a loading probability density function, which is based on the recent data records forming significant wave probability density function and its corresponding mooring tension probability density function of rope through beta distribution technique; secondly to form a strength capacity probability density function, which is given by a rope manufacture company. Finally, the breaking risk of mooring lines is obtained by calculating the intersection area of loading and strength capacity probability density functions. The results show that the cage with a portal frame has good performance in general, especially when the sea states are rigorous. In other words, the frame-cage could maintain about 2 times net volume compared with the cage without a frame. However, the advantage of frame-cage is not obvious when the sea states are mild. Besides, the distance of frame ropes to the cage will also affect the net volume deformation, the trend shows that the net volume deformation increases with the decreasing of the distance of frame ropes. Finally assuming there are four typhoons per year attacking on the net cage system, the recommended replacing period of nylon mooring line (diameter 55 mm)is about 7 years, while for PET mooring line (diameter 50 mm)is about 13.4 years. The failure risk probability of nylon and PET mooring lines at the recommended replacing years are about 0.49 and 0.48~0.49 respectively. Therefore, we strongly recommend marine farmers to use PET ropes instead of nylon and have to replace those ropes before the failure occurs.
16

Development of an actuation system for a specialized fixture: providing two degrees of freedom for single point incremental forming

Fatima, Mariam 01 February 2013 (has links)
In this thesis, an actuation system is developed for a Two-Axis Gyroscopic (TAG) adapter. This adapter is a fixture with two auxiliary axes which is used for the Single Point Incremental Forming (SPIF) technique to enhance a three-axis mill to have five-axis capabilities. With five-axis mill capabilities, variable angles between line segments of the toolpath and the tool can be obtained. To achieve specialized angles between a line segment and the SPIF tool, the sheet is rotated. Inverse kinematic equations for the TAG adapter are derived to calculate the required rotations for the TAG adapter’s auxiliary axes for a line segment of a toolpath. If the next line segment requires a different orientation of the sheet, the sheet is rotated while the tool follows the rotation of the sheet to maintain its position at the connecting point of the line segments of the toolpath. Five equations of motions are derived to calculate the three translations of the mill and two rotations of the TAG adapter’s frames, during forming. A toolpath execution algorithm is implemented in MATLAB which uses the five equations of motion to execute a toolpath. The algorithm generates an array of data points that can be used by a Computer Numerically Controlled (CNC) machine to follow a desired path. A visual representation for the execution of the toolapth is implemented in MATLAB and is used to illustrate the successful completion of a toolpath. A computer controlled motor system is selected and tested in this thesis which will ultimately be integrated with a worm gear system and a CNC machine to develop a full CNC actuation system. / UOIT
17

Array microscopy technology and its application to digital detection of Mycobacterium tuberculosis

McCall, Brian 16 September 2013 (has links)
Tuberculosis causes more deaths worldwide than any other curable infectious disease. This is the case despite tuberculosis appearing to be on the verge of eradication midway through the last century. Efforts at reversing the spread of tuberculosis have intensified since the early 1990s. Since then, microscopy has been the primary frontline diagnostic. In this dissertation, advances in clinical microscopy towards array microscopy for digital detection of Mycobacterium tuberculosis are presented. Digital array microscopy separates the tasks of microscope operation and pathogen detection and will reduce the specialization needed in order to operate the microscope. Distributing the work and reducing specialization will allow this technology to be deployed at the point of care, taking the front-line diagnostic for tuberculosis from the microscopy center to the community health center. By improving access to microscopy centers, hundreds of thousands of lives can be saved. For this dissertation, a lens was designed that can be manufactured as 4×6 array of microscopes. This lens design is diffraction limited, having less than 0.071 waves of aberration (root mean square) over the entire field of view. A total area imaged onto a full-frame digital image sensor is expected to be 3.94 mm2, which according to tuberculosis microscopy guidelines is more than sufficient for a sensitive diagnosis. The design is tolerant to single point diamond turning manufacturing errors, as found by tolerance analysis and by fabricating a prototype. Diamond micro-milling, a fabrication technique for lens array molds, was applied to plastic plano-concave and plano-convex lens arrays, and found to produce high quality optical surfaces. The micro-milling technique did not prove robust enough to produce bi-convex and meniscus lens arrays in a variety of lens shapes, however, and it required lengthy fabrication times. In order to rapidly prototype new lenses, a new diamond machining technique was developed called 4-axis single point diamond machining. This technique is 2-10x faster than micro-milling, depending on how advanced the micro-milling equipment is. With array microscope fabrication still in development, a single prototype of the lens designed for an array microscope was fabricated using single point diamond turning. The prototype microscope objective was validated in a pre-clinical trial. The prototype was compared with a standard clinical microscope objective in diagnostic tests. High concordance, a Fleiss’s kappa of 0.88, was found between diagnoses made using the prototype and standard microscope objectives and a reference test. With the lens designed and validated and an advanced fabrication process developed, array microscopy technology is advanced to the point where it is feasible to rapidly prototype an array microscope for detection of tuberculosis and translate array microscope from an innovative concept to a device that can save lives.
18

A STUDY OF ENERGY, CARBON DIOXIDE EMISSIONS AND ECONOMICS IN MACHINING: MILLING AND SINGLE POINT INCREMENTAL FORMING

BRANKER, KADRA 05 December 2011 (has links)
A simple model that includes energy and carbon dioxide (CO2) emissions in the economics of machining is proposed, which has been published in the highly respected and cited journal, Annals of CIRP (International Academy for Production Engineering). This is a timely analysis in current government discussions on a proposed carbon tax or a carbon cap and trade regime and greater energy efficiency. The new cost model is based on life cycle analysis methodology for the initial part production. An illustrative example is given showing that the cheapest electrical grid should not be chosen, if it also has the highest CO2 emissions. Accurate pricing is important, because the more expensive product was highly dependent on the carbon price. A comprehensive review of machining economic models is covered. However, there is a dearth of actual machining data in the literature. This work includes studies in milling and single point incremental forming (SPIF) which can be used by other manufacturing engineers in their machining economic model development. The first milling study involved simple straight cuts. In general, as feed rate (FD) increased (increasing the material removal rate, MRR), the energy consumed decreased as process time decreased. In contrast, as spindle speed (N) increased, energy consumed increased, since more power is drawn by the motor, without a process time reduction. Given the inverse power relationship observed for the time, energy, process CO2 and cost against MRR, the recommended parameters were the same at the highest FD and lowest N permissible. In the second milling study with constant N for a more complex part (sprocket), similar relationships were observed. However, for sprockets made at constant chip load (allowing FD and N to change together), there were varying prescribed MRRs for time, energy, process CO2 and cost minimization. The SPIF studies showed a similar relationship to the constant N milling, and, that results for a simple part can be extrapolated to improve efficiency in more complex parts. Finally, although the energy and carbon costs represented a small contribution to the final cost, their significance increased for higher efficiency parameters or user conditions, e.g. low labour rate. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2011-12-03 19:58:07.76
19

Modelo hidrodinâmico heurístico para análise de navios petroleiros amarrados sujeitos à ação de correnteza. / An heuristic hydrodynamic model for the analysis of moored ships under current action.

Alexandre Nicolaos Simos 03 September 2001 (has links)
O presente trabalho propõe um novo modelo hidrodinâmico para avaliação das forças oriundas da ação de correnteza marítima uniforme sobre o casco de navios petroleiros amarrados. A modelagem é válida para qualquer ângulo de incidência de correnteza e sua aplicação é voltada, especialmente, ao estudo dinâmico de sistemas FPSO (Floating Production Storage and Offloading systems), muito embora seu campo de aplicação possa facilmente ser estendido a problemas correlatos em engenharia naval. O modelo ora apresentado depende basicamente das dimensões principais do casco, necessitando de um conjunto bastante pequeno de parâmetros a serem determinados experimentalmente. Essa natureza quase-explícita da modelagem constitui sua principal vantagem face aos demais modelos usualmente empregados, e a mesma advém exatamente do contexto mais restrito para o qual foi formulado. O modelo heurístico estendido foi elaborado com base em um modelo estático previamente desenvolvido por Leite et al. (1998). Foram incorporados os efeitos provenientes do movimento de rotação do casco, tornando o modelo aplicável ao caso geral de movimentos do navio no plano horizontal. A determinação destes efeitos foi fundamentada em uma abordagem heurística, combinando-se estimativas semi-empíricas para as forças decorrentes de diferentes padrões de escoamento fluido no entorno do casco, padrões estes associados a faixas de ângulos de incidência distintas. As estimativas de força e momento em movimento combinado de translação e rotação do casco foram validadas a partir de resultados experimentais obtidos em ensaios de yaw-rotating, conduzidos com modelos de diferentes navios petroleiros, em duas condições de carregamento distintas. ) Posteriormente, a verificação experimental foi ampliada, analisando-se a adequação do modelo hidrodinâmico ao estudo de instabilidade dinâmica de navios atracados por intermédio de um cabo de amarração (hawser), fenômeno conhecido em engenharia naval como fishtailing. Em paralelo ao desenvolvimento do modelo hidrodinâmico e sua validação experimental, objetivos primeiros deste trabalho, procede-se a uma revisão crítica das diferentes abordagens teóricas comumente empregadas, baseada nos principais aspectos hidrodinâmicos envolvidos em aplicações práticas de navios amarrados em sistemas offshore. Assim, face à complexidade do problema em questão e dada a profusão de modelos teóricos existentes na literatura, mais do que a defesa de um ou outro método de análise, procura-se fornecer um orientação consistente para que o projetista de sistemas oceânicos possa escolher, com maior confiança, a abordagem mais apropriada para a aplicação em questão, ciente de suas vantagens e eventuais limitações. / A new hydrodynamic model for the analysis of current forces acting on moored tanker ships is proposed. The theoretical model is valid for any angle of attack of the current and is intended, primarily, for the analysis of FPSO (Floating Production Storage and Offloading) systems, although its application may be easily extended to other correlated problems in ocean engineering. The model depends basically on the ship main dimensions and requires few external parameters to be derived. This quasi-explicit nature certainly constitutes the model main advantage and it was only possible due to the more restricted context it was derived for. The extended heuristic model, as it is called, was based on a previous static version presented by Leite et al. (1998). The hydrodynamic effects arising from the ship yaw motion were now incorporated, making the model able to cope with the problem of combined drift-yaw motions. Yaw velocity influence was determined by means of a heuristic combination of semi-empirical formulations of force and moment components, resultant from distinct fluid flow patterns, each one related to a different range of angles of attack. Force predictions were validated through confrontation with yaw-rotating experimental results, obtained for different tanker models in distinct loading conditions. It was also verified experimentally that the model is capable of predicting the hydrodynamic forces involved in the unstable dynamic behavior of asingle-point moored tanker, when subjected to a steady ocean current, known as fisthailing phenomenon. A critical revision of the different theoretical models at hand represents a supplementary purpose of this work. This revision was performed based on the main hydrodynamic aspects involved in common offshore applications of moored tanker ships. ) Therefore, instead of a passionate defense of any particular theoretical procedure, the work aims to provide a consistent orientation in order to help the offshore system designer to choose, between the various hydrodynamic models, the one that is more suitable for the analysis of a specific project, confident on its advantages and aware of its eventual limitations.
20

Metodologia para avaliação da capabilidade de controle de superfícies técnicas usinadas em torno de ultraprecisão / Methodology to assess the capability of the control technical surfaces in ultraprecision turning manufacturing

Rosana Camargo 21 November 2005 (has links)
A nanotecnologia não é mais um sonho, já faz parte da nossa realidade, do nosso dia a dia. É considerada, por muitos, a quinta Revolução Industrial, uma revolução tecnológica de grande abrangência, que poderá causar impactos talvez sem precedentes na história. A soma anual dos investimentos nesta nova tecnologia é de bilhões de dólares. Devido às inovações oriundas da nanotecnologia, os processos da manufatura e a medição de ultra-precisão vêm se desenvolvendo a cada dia. A nanotecnologia fez da usinagem de ultraprecisão com ferramenta de diamante uma grande aplicação na produção de itens de alto volume, tais como: disco de memória de computadores, lentes de contato, moldes de dentes, cilindros para impressão, espelhos metálicos. A alta integridade da superfície é requerida em todos os itens obtidos por este processo. Em conseqüência, é necessário um método de medição que seja o mais exato possível, isto é, que chegue a resultados o mais próximo possível do valor verdadeiro. Mas o que significa exatidão para uma análise ideal da superfície, uma vez que não existe referência para isso? Superfícies têm sido avaliadas por meio da medição da rugosidade, a qual consiste na determinação de um valor médio, de vários setores, dentro de valores limites preestabelecidos. A metrologia, através de seus métodos e princípios, é um importante instrumento para validar modelos e teorias. O conceito que \"uma vez testado, passa a ser aceito em qualquer lugar\". Daí a crescente necessidade de resultados de medições confiáveis que possam ser validados em qualquer lugar e a qualquer tempo. Assim, um caminho a ser seguido é o de se entenderem profundamente todos os métodos e princípios envolvidos nas operações de medição de rugosidade. E para que um método seja metrologicamente válido (ou aceitável), faz-se necessário realizarem-se comparações de diversas medições, de um mesmo mensurando, utilizando métodos diversos. Havendo discrepância nos resultados, é uma evidência de que as premissas e hipóteses levaram a acreditar que a teoria ou modelo adotado deve ser reavaliado. Este trabalho selecionou os três métodos mais utilizados na caracterização da integridade de superfícies técnicas obtida em torneamento de ultraprecisão com diamante, e descreveu uma metodologia para a avaliação da capabilidade do processo de controle de superfícies técnicas usinadas em torno de ultraprecisão. / Nanotechnology is no longer a dream. It is part of the real world. It is considered by many people as the fifth Industrial Revolution, a technological revolution of great impact in history. The world annual investment in this technology reaches billions of dollars. Due to innovations related to nanotechnology, ultraprecision manufacturing processes and metrology is developing steeply. Nanotechnology made single point diamond turning an important mass production process of, for instance, computer hard discs, contact lenses, moulds, printer cylinders, metallic mirrors, etc. High grade surface integrity is required of items produced by this process. As a consequence, it is necessary to use a measurement method which is most accurate as possible, i.e., resulting in a value as close as possible to the true. But what does true mean if there is no reference for that? Surfaces have been assessed by roughness measurements which determines a mean value of several sectors within pre-determined limits. Metrology, with its methods and principles, is an important instrument to validate models and theories. The concept, once tested, becomes accepted everywhere. Therefore the increasing necessity of reliable measurement results which may be validated anywhere and any time. Thus, it is essential a deep understanding of all methods and principles involved in roughness metrology operations. For a method to be metrologically accepted, it is necessary that it is compared with different methods. In the event of existing discrepancies, the premisses and hypotheses which fundamented the theory or model should be reassessed. Three of the most used methods have been selected to characterize the surface integrity of technical surfaces generated by diamond turning. A methodology to assess the capability of the process of control of those surfaces is proposed.

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